Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Mon, 23 Apr 2018 19:45:06 +0200
From:   Joerg Roedel <jroedel@suse.de>
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Joerg Roedel <joro@8bytes.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>,
        "H . Peter Anvin" <hpa@zytor.com>,
        the arch/x86 maintainers <x86@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-mm <linux-mm@kvack.org>, Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@intel.com>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Juergen Gross <jgross@suse.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Borislav Petkov <bp@alien8.de>, Jiri Kosina <jkosina@suse.cz>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Brian Gerst <brgerst@gmail.com>,
        David Laight <David.Laight@aculab.com>,
        Denys Vlasenko <dvlasenk@redhat.com>,
        Eduardo Valentin <eduval@amazon.com>,
        Greg KH <gregkh@linuxfoundation.org>,
        Will Deacon <will.deacon@arm.com>,
        "Liguori, Anthony" <aliguori@amazon.com>,
        Daniel Gruss <daniel.gruss@iaik.tugraz.at>,
        Hugh Dickins <hughd@google.com>,
        Kees Cook <keescook@google.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Waiman Long <llong@redhat.com>, Pavel Machek <pavel@ucw.cz>,
        "David H . Gutteridge" <dhgutteridge@sympatico.ca>
Subject: Re: [PATCH 00/37 v6] PTI support for x86-32
Message-ID: <20180423174506.mpbpnvfzv6fmpbzy@suse.de>
References: <1524498460-25530-1-git-send-email-joro@8bytes.org>
 <CA+55aFwg75rOXN5Q0qHf_GF-hnVo8mjxnTo2FbM993fuc8x7Gw@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CA+55aFwg75rOXN5Q0qHf_GF-hnVo8mjxnTo2FbM993fuc8x7Gw@mail.gmail.com>
User-Agent: NeoMutt/20170421 (1.8.2)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, Apr 23, 2018 at 09:45:38AM -0700, Linus Torvalds wrote:
> Just one question: have you checked the page table setup for the
> basics wrt the USER bit in particular?

Just checked that and there are no pages with GLB and USR set, not even
a vdso page.

> No global pages should be marked PAGE_USER, with the possible
> exception of that nasty old vsyscall page.

The vsyscall page does not exist on plain 32 bit, no? All I could find
there is the vdso page, and that has no compat mapping anymore in recent
upstream kernels. To my understanding the vdso page is mapped into the
user-space portion of the address space. At least that is what I found
while looking at this, but I might have missed something.

I actually ran into a vdso issue when porting these changes to 3.0
(where there still is a compat vdso mapping in the fixmap) so I checked
my upstream code too, but didn't find the code to setup a vdso in the
fixmap.

> And it would be nice to verify that the page tables for kernel
> mappings also don't have PAGE_USER on them, although again that
> vsyscall page can cause problems.

Checked that too, all USR mappings are below PAGE_OFFSET.


Regards,

	Joerg